1. Technical Field
The present invention relates to integrated circuit packaging, and more specifically, to using alpha particle shields in integrated circuit packaging.
2. Related Art
In flip-chip technologies, solder bumps are typically formed on top of a semiconductor chip (i.e., integrated circuit IC). Each solder bump is formed directly on a bond pad of the chip. Then the chip is flipped face down and then aligned to a package/substrate so that the solder bumps are bonded directly, simultaneously, and one-to-one to the pads of the package/substrate (called package/substrate pads). However, for ceramic substrates, alpha particles (large subatomic fragments consisting of 2 protons and 2 neutrons) continuously emit from the substrate and enter the chip resulting in a large number of soft errors in the chip during the normal operation of the chip. Alpha particles are also generated from 210Pb contained in the solder bumps.
Therefore, there is a need for a structure (and a method for forming the same) that reduces the number of alpha particles that enter the chip.